Differences in the secondary metabolites of different varieties of black tea and evaluation of their disease-resistance activity

Rich secondary metabolites render black tea its unique flavor and health benefits, making it the most widely consumed tea in the world. Yet, few studies have investigated the differences in secondary metabolites between black-tea varieties and whether secondary metabolites have antidisease activity. Using gas chromatography-tandem mass spectrometry metabolomics and the Traditional Chinese Herbal Medicine Systems Pharmacology Platform database, this study investigated differences in the secondary metabolites of varieties of black tea, including Fuding Dabai (FD), Golden Guanyin (JGY), Golden Peony (JMD), Qianmei 601 (Q601), and Qiancha 1 (Q). Then, the antidisease activity of their secondary metabolites was evaluated. A total of 657 secondary metabolites were identified in the different black-tea varieties. Among them, 183 metabolites had antidisease activity, 113 were key active ingredients in traditional Chinese medicine (TCM), 73.22% had multiple antidisease activities, and all were mainly flavonoids and phenolic acids. The specific differential metabolites of FD vs JGY, FD vs JMD, FD vs Q, and FD vs Q601 and their disease-resistance activities were (67, 17), (24, 5), (26, 6), and (65, 8), respectively. The main enriched metabolic pathways were phenylpropanoid biosynthesis, biosynthesis of secondary metabolites, flavonoid biosynthesis, and metabolic pathways, with four, four, six, and five key metabolites, respectively. Flavonoid and phenolic acid secondary metabolites were more correlated with antidisease activity and key active TCM ingredients. Conclusion: The types of secondary metabolites were consistent among the different black-tea varieties, while the relative contents differed significantly, with greater differences in secondary metabolites between JGY and Q601. Flavonoid and phenolic acid secondary metabolites were the main contributors to the differences in secondary metabolites and the disease-resistance activity of different black-tea varieties, followed by lignans with coumarins, alkaloids, and tannins also contributing to disease-resistance activity. These findings improve our understanding of the secondary metabolites and health benefits of different varieties of black tea.